Compact high-intensity discharge lamps (HID lamps) are widely used as light sources employed in vehicle headlights and projectors.
There are descriptions of microwave electrodeless lamps in Japanese Patent Application Laid-Open (JP-A) Nos. 2008-140575 and 2008-140576, configured with a transparent vessel including an inflation section with a sealed space in which a light-emissive substance is sealed and a pair of capillaries connected to face the inflation section; internal conductors sealed into each of the capillaries; and coils acting as external conductors wound at the outer periphery of the capillaries over substantially the length direction range of the internal conductors. Microwave electrodeless lamps configured in such a manner are illuminated by microwaves picked up by the coils, however they have low illumination intensity which is detrimental to practical implementation.